Method and apparatus for forming tubular ceramic bodies



M h 1 1954 J o EVERHART ET AL 2,671,939

METHOD AND APPARATUS FOR FORMING TUBULAR CERAMIC BODIES 2 Sheets-Sheet 1 Filed April 28. 1950 a a F iily ll a BY J, M

, I I I %m ATTORNEY J. O. EVERHART ET AL March 16, 1954 METHOD AND APPARATUS FOR FORMING TUBULAR CERAMIC BODIES 2 Sheets-Sheet 2 Filed April 28, 1950 was Patented Mar. 16, 1954 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR FORMING TUBULAR CERAMIC BODIES Application April .28, 1950, Serial No. 158,894

Claims.

This invention relates to the manufacture of ceramic pipe members and other similar hollow cylindrical bodies. It is concerned primarily with pipe members of the type formed by wrapping extruded webs, sheets or strips of ceramic and cementitious compositions, while the same are in a plastic and formative condition, on or about a rotatable mandrel or core.

Ceramic pipe of, for example, the kind used in forming underground conduits, is produced most commonly by extruding a clay column and thereafter firing the same. Inasmuch as such pipe is required to possess certain varying diameters, the cost of extruding dies and related machinery utilized in its manufacture becomes quite burdensome, a condition which is reflected in the cost of the pipe.

Therefore, in order to reduce the amount of equipment required, and yet to provide means to produce pipe in a variety of difierent diameters and lengths, including diameters greater than those now produced by conventional extrusion means, the present invention has for its primary object to provide an improved means and method of forming such pipe, in whole or in part, by extruding strips of ceramic material in a plastic formative condition through the use of relatively smal1 and inexpensive extruding machinery, and then wrapping such strips in helical closely adjoining and relatively united convolutions about a rotatable and longitudinally movable roll, mandrel or core. In this manner ceramic pipe of any desired diameter or length may be produced from one or more standard relatively small size clay-extruding machines, since the latter serves only to produce a strip of plastic material having a desired cross-sectional configuration, said strip being then wound about a manderl or similar member possessing a diameter and length which will produce the dimensions desired in the finished pipe.

It is another object of the present invention to provide a novel method and apparatus for producing ceramic pipe by the strip extrusion and mandrel wrapping method in which the plastic and formative strip of material has imparted thereto a preformed curvature before the strip is wrapped about the core or drum, whereby to enable the strip to assume readily the circumferential configuration of the core, drum or mandrel about which it is Wrapped with but small likelihood of transverse cleavages or fissures developing therein.

It is another object of the invention of forming ceramic pipe by the wrapping method defined in which the strip material is roughened or scored along its side edges and treated with an adhesive slurry, slip or other bonding material, so that adjoining convolutions thereof maybe pressed closely together and sealed or bonded to one another to form an integral and continuous bond between said convolutions throughout the length of the pipe.

It is a further object of the invention to provide a method and means for forming ceramic pipe in which the ceramic material in a plastic state is extruded in the form of a sheet or web of a width which corresponds to the length of the pipe to be formed therefrom, the said web or sheet being wrapped about the core or mandrel and united by a single straight longitudinally extending joint. In attaining this last set forth object, the present invention provides a sheet or web extrusion with a curved outlet by which the sheet or web when extruded possesses a curved or arcuate form readily adapting the same to the curvature of the core or mandrel on which it is applied.

A still further object of the invention is to provide a method and apparatus for producing strong, serviceable ceramic pipe in a more facile and economical manner than heretofore.

Still a further object of the invention resides in providing a method and means for forming ceramic pipe in which use is made of extruded strips of material having cross-sectional configurations by which either butt or scarf joints may be provided between adjoining convolutions of the strips when the same are wound upon a core or mandrel.

Another object of the invention is to provide apparatus for forming pipe, or other similar hollow cylindrical objects, in which strips of plastic material are wrapped in closely joining helical coils about a revolving drum or mandrel, and wherein said drum or mandrel is mounted for rotation about a, substantially vertically disposed axis, so that the convolute strips of plastic material are disposed substantially horizontally as they are being wrapped around the drum or mandrel and held in a supported manner, preventing distortion of said coils, which is apt to occur by their own weight when the same are wrapped around a horizontally positioned drum or mandrel.

Still another object of the invention is to provide pipe-forming means of the character under consideration in which the side surfaces of the plastic coils as the latter are being extruded and wrapped around a revolving drum or mandrel are lightly scored or scarified in a manner producing intersecting grooves therein, whereby to enable a bonding slip to be applied to such scarred or grooved surfaces to produce an improved union between tthe @contiguous surfaces of adjoining coils.

Still another object of the invention is to provide a method whereby a hollow extrudeil strip or column may be helically wound into a pipe with an appreciable reduction"in.thelam.ount of material required over that employed for forming solid-walled pipe anladva'ntage .ofzthe hollow spirally wound pipe resting in :reducing the Weight of large-diameter pipe, making feasible the manufacture of pipe in diameters which would be otherwise prohibitively'heavy.

With these and other objectsiandiadvantages in view, the invention consists in the novel features of construction, combinations of elements, arrangement of parts, including certain novel -steps 'o'f operation and manner of procedure, all or which "are hereinafter more fully set forth and claimed.

Inthe accompanying drawings Fig. 1 is a. 'top:pla11 view, partly in horizontal cross section, of apparatus "formed in accord- :ance with :the present invention ifor producing ceramic pipe by the strip-wrappingrme'thod;

-qi'ig. 2 isa side elevational View of theapparatus disclosed iniFig; 1';

Fig. 3 is a detailivertical'sectional :view taken mmthe linel3- 3 of Fig.1 2;

Fig. 4 15a horizontal :sectional view taken on the plane-'disclosedi-by:theiline i- 4 of Fig.3;

Fig. :5 'is a "detail iverti'calssectional view, rpartly in perspective, disclosing ipipe reformed :by the present invention from ihelically wrapped strips of 'plastic material fin which the acent edges or the :adjoining 'convolutions of :the strips are :united flay-straight butt type joints;

Figs. :6, .7 :andz8 gare' views similar :to Fig.5 disclosing modified ."types :of joints IOf 1the overlapping or scarf type;

Fig. 9 is :a Itop plan view, partly ;in horizontal :section, of re modified form of apparatus :utilized :by :the .present invention zfor the formation :of ceramic zpipe by :extrusion with :webs .or :sheets ,of ceramic material in a plastic :..condition .and wrapping:the :same on a drum nor mandrel;

lFig. :10iis averticalssectional-view-.takenmnzthe iFig. :11 :is a detail :view :of .a lap :jo'intrproduced zbyithezapparatus;ofiFigs.-.9.-and 1.0.;

:Eig. 12 is azdetailcview ofia ceramicgpipe formed in accordance with the present invention :and

zhaving oneendithereoi formed with .a bellssocketa fragmentary detail 'side elevational view:disclQsing :ZL modified 'form of presser toot, -.u12ilizing.azroller :Fig. 14 21s .-.a wview .of a horizontal mandrel which :the extruded coils :are .supported :against sagging whenepplied ito -.the;mandrel1by;rollxle- 'VlELBS.

Referring :to 'the ;drawings, rand more particuilarly :to Figs. 11110 4: Tthfil'EQf, :therelhas sheen ,dis- =1 closed at :15: an :extruding :ma-c'hine pf athe :type ;used in dihe 'ceramic viindustry for extruding rpugged .clay, brick columns rand gother :products "which possess ?the ssanre cross-sectional "confi uration throughout the length thereof. ithis --mstance, .thezmachine E hasbeenishownlas in- :cluding ardieihead t5 andraninternahauger :l-fi. pI here anded :to the columnidischarging side (of :thexlie headaimllow icolumn-formmg :exten- :"sinn i which, as shown in Big. 31, :possesses war ill) curvilineal 0r arcuate configuration, the shape of the extension being such that a moldable strip or column of clay emerging from the nozzle is, prior to its application to the cylindrical outer surfaces :of 1a formaor imandrel d3, of a :preformed arcuate shape adapted to=the curvature of =the'cylindrical surfaces of the form or mandrel on which it is (applied.

In accordance with the present invention, the .form oriman'drel T8 is disposed so that its longitudinal axis extends vertically, or at a slight angle t'or t'he wertical, the lower portion of the form-or-mandrel'being provided with an annular bottomflange l9.on the upper surface of which ;the extruded strip or web 20 of ceramic ma- "terial'in a formative state is initially placed and -suppnrted, sosas ito enable the strip or web to be wrapped in closely adjoining convolute coils around the cylindrical outer surface of the form or mandrel. By using the vertically positioned form for mandrel with its bottom flangef-it will be noted-that improved support 'is provided for the 'strip or web 20 over *previous -'c1isclosuresiin which 'the form or mandrel is horizontally positioned. -When *horizontally positioned, the plas- -'tic *strip or web =tends to elongate :and 'sa'g, :proilucing 'an exit-of-round condition. 'By :stacking the convolute spirals :of the :web ors'trip vertically, as shown herein, such sagging is effectively precluded.

However, if it is desired to employ-a'horizonta'l -mandrel, the sagging o'f t-he aextruded plast'rc column wrapped around such a horizontal mandrel may be' prevented' by th employmentofrone -or more small-diameter rolls, indicated at 2011. The roll -or :ro'lls 20a "serve to prevent :drooping or sagging on the part of the-pipe-Tormingpoils 'o'f -such a h-orizontally positionedrmandrel. 311; is, of course, possible to use a roll ;or rolls 221111 :in connection with a vertical mandrel, i'f.desired :as indicated at 2Ub'in'Fig. 1.

l lre drum 'or' mandrel .18 may .be supported :for rotation by a screwshaft's. "This shaft may inc formed or operated in two .ways: For cexample, the shaft may be-provided :witha tthread, the pitcher which is-equal to'that 0f7th6 clay wrapk ping, the shaft S being non-:rotatably mountetl. With this :construction, the "mandrel :must :be positively driven :at a :speed tt-o :accommodate :tlre :c'lay extrusion speed and later :removed 'when hardened. z-Seconddlhe threadedshaftfijnay be rotated, but the-mandrel thereon must ;be :positively .driven :to accommodate the clay extrusion speed, :and :also thescrew shaft must :be :rotated 'at a speed dependent :upon .zmandrel speed sand screw-pitch.

Another feature vof ;the present invention ;r.e- :sides in scoring ,or :scarifying :the :contiguous .sur-- .races of :the strip or web :to :effect rm improved .unionltherebetween. 1Such grooving orsscarifym may be accomplished conveniently iby :proviizlingzthe couteriend of Lthe nozzle-extension it! with :a :bracket r24 .containing *a shearing 22 zinwhichzis :monnted for rotation a :motoredriven shaft 2:3, :the latter being provided .at mic-"end with:a disk 24. iEccentrically :pivoted (t0 :one face of :this :disk, as :at 2,5, :is :a crank the latter in tturn .beingpivotallyrsecured at onetendzqf alongitndi- -nal1y:recip1:ocable L'Efld ;2'l, the zlatter being sslid- ;ably mountediin :a bearingflfl. Iodine-y be provided with :a -.plura'lity :of :spaced pointed pro- -iections 19 which are :adapted .to 13011173613 the under surface of .the zstripror zuaeh 220 as the leavesstheputlet. of the :nozzie :extension VI 1, :prutmcingdzhe transverse grooves 23.! in athexsm' face 30 which substantially perpendicularly intersect longitudinally extending grooves 32 formed in the surfaces 30 by projections formed in the outlet or discharge mouth of the extension I1.

To this grooved or scarified surface, there is applied by means of the pressure pipe, indicated at 33, a slurry or bonding slip, as shown, which enters the grooves 3! and 32 and spreads over the surfaces of the strip therebetween to form an improved bond between the contiguous surfaces of the strip after the latter have been helically wrapped and formed around the mandrel or mold l8. Also, use may be made of a spring pressing foot 34. This foot is carried by the outer end of the nozzle extension I! and, as shown in Fig. 2 particularly, the resilient outer end of the foot is so disposed as to engage the upper surface of the strip or web 20 as the latter is being coiled around th form or mandrel I8, the foot 34 serving to apply positive pressures in a downward direction to the strip or web to cause the desired union or bond between adjacent surfaces of the strip or web in producing the completed and finished tubular portion. As shown in Fig. 13, the presser foot may be provided at its outer end with a resiliently supported roller 34a which maintains a pressure on the clay column or strip as it is wrapped around the mandrel to force the same into bonded engagement with an adjacent coil.

In this form of the present invention, the strips or webs are substantially rectangular in transverse construction, as shown in Fig. 3, so that their bonded or mating surfaces are fiat and form butt joints between contiguous surfaces. In Fig. 5, this butt joint construction has -been disclosed although the strip or web is extruded in hollow form, rather than solid, the hollow interior of the strip or web being indicated at 35. Various other types of joints may be used. For example, in Fig. 6, the contiguous edges of the strip or web are shaped to produce interfitting tongues and recesses, as indicated at 36 and 31, forming an overlapping or scarf joint. A somewhat similar arrangement has been suggested in Fig. 7 in which a scarf joint is produced by providing adjoining surfaces of the strip or web to form V-shaped grooves 38 which receive V-shaped extensions 39'having reversely beveled outer surfaces. In Fig. 8, interfitting tongues and grooves 40 and 4| are shown in the formation of a mechanically secure union between the adjacent surfaces of the coils.

Another variation of the present invention is to be found in Figs. 9 through 11 of the drawings. In this form of the invention, the clayextruding apparatus includes a head 42 having a relatively wide chamber 43 formed therein which communicates with the lower end of a vertical or otherwise positioned barrel 44 in which is mounted a rotatable clay-advancing auger 45. Disposed for reciprocation in the chamber 43 is an elongated piston 46 with which is connected a rod 41, the latter passing through a bearing 48 in one side of the head so that the rod may be connected with a source of power, not shown, such as a hydraulic motor, for imparting controlled movement to the piston to cause the forced expulsion from the chamber 43 of the clay mass contained therein.

As in the previously described form of the invention, the outlet of the head includes a restricted nozzle extension 49 which is preferably of arcuate formation in the region indicated at ill 50, so'that the strip or web 20 of clay will possess an arcuateform when the same is applied to the cylindrical outer surfaces of the form or mandrel iii. The strip or web is of approximately the full length of the finished tubular article to be produced therefrom, avoiding the necessity of the helical wrapping required in the previously described form of the invention. After the strip or web has'been wrapped once or more times around the outer periphery of the drum or mandrel l 8, the said strip or web may be transversely severed to complete the shape of the final article and separate the same from the material contained in the extruding apparatus.

If the pipe to be formed by the present apparatus is of the bell and spigot type, as indicated at 5| in Fig. 12, an outer band or collar 52 may be formed around one end of the tubular body 53 of the pipe to produce the bell socket 54.

The present invention thus provides an improved method and apparatus for forming cylindrical ceramic pipe sections of varying diameter, wherein an extruded web or strip of clay, or other ceramic material, in a plastic state is either spirally wound about a rotating and longitudinally movable form or mandrel, or wherein the extruded web is so formed as to have a width equal to the length of the pipe section desired. In the latter form of the invention, it will be noted that the web is merely lapped about a form or mandrel and joined at its respective free ends in a lap weld, as indicated at 55. By the term ceramic material, as used herein, it is contemplated that the same shall embrace within its definition such pipe-forming materials as clay, cement, concrete and also cement and mineral fiber mixtures, all of which are now commonly used in the formation of pipe, tile and tubing.

In the form of the invention illustrated in Figs. 1 through 3, it will be observed that the present invention provides for the formation of pipe by winding a substantially continuous extruded strip or web of clay or the like about a vertical or horizontal rotatable mandrel, while compressing the successive convolutions of plastic material endwise of the material and applying an adhesive slip, or other suitable bonding material, to the adjoining surfaces of the clay web in obtaining an integral-weld or bond between the successive coils of the applied helix. The web or strip may be extruded in a manner providing overlapping or interlocking mating edge formations, whereby to further facilitate the bonding of successive convolutions to one another.

In the form of the invention shown in Figs. 9 and 10, instead of spirally winding a continuous web of clay about a rotating mandrel, the present invention provides for the extrusion of a relatively wide sheet or web of clay which is wrapped coextensively over the rotating mandrel and lapwelded at its respective ends. Another feature of this invention resides in the use of the curved extrusion nozzle which imparts to the clay web, sheet or strip a radial curvature conforming roughly to that of the outer surface of the mandrel or form upon which it is to be disposed, so that during the wrapping of the plastic material around the mandrel, severe internal stresses and strains are prevented from being set up within the composition of the plastic material to produce cracking or fracture thereof. This feature is highly advantageous in preventing the possibility of breaks in the web of plastic material, as would be apt to occur if the web were to be bent around a drum-like mandrel after being (extruded in straight :fm'm. .llt will she understood that .iollowing the wrapping 9f the plastic -.column about the unandrel, the some is paused :to set or harden (and zis thereafter re- :moved rtrom the :mandrel and subjected to dining temperatures lwithinxa kiln toproduoe the finished conduit section.

While we :have .set forth in' detail certain preitem-zed embodiments of =our present invention which we have ,found to die desirable in carrying the :same .into practice, it will be understood dahat inosoadoing, we 'do :not limit the invention to the precise structural details, icombi-nations of parts and sequence of operations described and illustrated, since we :reserve (the right .to employ all istrluctm'al variations -.or modifications tailing itairly within the spirit'andscopepf the followin ;claims.

.1. Apparatus for producing tubular bodies of ceramic composition comprisin: a vertically .disposed rrevoluble core hauing :cylindrical outer surfaces and ran annularseating flange, appara- -tus -for mixing and extruding :ceramic matenial .in the form of .a plastic strip, said apparatus having an outlet disposed contiguous to the cylindrical peripheral surfaces of saidcore, and -being :operable to lextrude a plastic ceramic strip having the same general :cunvature [as the periphvoral :surface of said core :and to discharge the :strip .-for .helical winding about said core up- ,wardlyl'from the peripheralflange thereoLmeans for applying downwardly directed compacting forces to the strip as the same is wound about said core, andnneans iormotating said core and moving the same :at -;a controlled rate of speed longitudinally with respect to its axis of rotation.

;2. Thelmethod-of making ,tubular articles .f-rom -a plastic strip (of \ceramic composition which icompiuses .the steps .of extruding .an ,arcuately curvedvceramic stripaof plastic-coinpositioncforming said curved strip into .a tubular article .by coiling the same on a rotating :mandrel, and .roughening the side surfaces of .said strip as ,thesame lis beingextruded-and prior .to applica- :tion *to said mandrel to dorm slurry-receiving :grooves in said surfaces to ,produce bonding thereof when applieddnadioining ,helical-coilson saidmandrel.

:3. The method .of making clay pipe, which :Q-ORLDIlSBS extruding :a :longitudinally cur,ued-colmm -.of clay .in .a plastic formative condition, wrapping said column .in relatively :tight tadxiaoently disposed .helical convolutions ,about a ,forming mandrel, applying llaterally directed i8 compressive domes to the (column when the same :is being wrapped about said zmandrel to bring the conyolutions :into close ,edgewise engagement, pressing the column against the outer surfaces of the mandrel, whereby to cause the coils ,to conform closely to :said mandrel surf aces and the configuration thereof during the formation cDf the :pipe, and thereafter (causing said column lof :clay :to set :and harden while on said mandrel.

*4. Theunethodaofrmaking clay pipe wlhichcomprises :extruding a longitudinally cunved column 'of (clay :in a (plastic iformative condition, wraprping said column .in relatively tight adjacently :disposed :helical :convolutions about ,a formin :mandreLapplying laterally directed compressive forces to the column when the same is bein wrapped about said mandrel to bring the resultingrconvolutions into close pipe-forming re- :lationship, pressing the column against the outer surfaces =.of the mandrel, whereby to cause the :convolutions to oonform'closely to said mandrel surfaces and the configuration thereof during the :formation of the pipe, and applying a bonding slurry =to 'the clay column at the time the latter .is wrapped {about said mandrel.

:5. who method of making clap pipe, which comprises: extruding a longitudinally curved plastic :clay column, wrapping said column helically about the exterior surfaces -.of a cylindrica-l :mandrel, maintaining the coils in close ,association with each other and with the (surface of the mandrel'on which the-same tare-wrapped, applying to the surfaces-of the column .a slip aOI slurry functioning as a bonding medium in ,uniting .said =,c oils, removing :the resultant tubular .body fromsaid .mandrel, and thereafter firing [the same under kiln zconditions.

JOHN O.

KARL E. KRILL.

ROBERT iE. .DINE. 1RLAND.-R. \VAN DER .iBEGK.

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